1. Field of the Invention
The present invention relates to a magnetic tape recording-and-playing apparatus such as a videotape recorder, and more particularly to a reel support for rotating reels in a magnetic tape cassette inserted in a magnetic tape recording- and-playing apparatus.
2. Related Art
A videotape recorder using a magnetic tape cassette has a tape-loading mechanism equipped therewith. Specifically the magnetic tape is pulled out of the cassette to be applied to the rotary head cylinder with the aid of the tape-loading mechanism. Thus, the rotary head cylinder is loaded with the magnetic tape with accuracy. To assure that the tape-loading mechanism works well it is necessary that the winding reel support and rewinding reel support of the videotape recorder be fitted in the winding reel and rewinding reel of the cassette with accuracy.
The reel support for rotating either reel in the cassette comprises a support stage, a reel post and blades, all of which are integrally connected to provide a whole body. The support stage is used for bearing the cassette reel, and the reel post stands upright on the support stage to be press-fitted in the hole of either cassette reel. The reel post has longitudinal slots made in its circumference, each containing a selected blade loosely, allowing one part of the blade to project outward from the longitudinal slot. When the reel post is press-fitted in the aperture of the winding or rewinding reel, the blades are engaged with some selected projections of the indented aperture of the winding or rewinding reel. Thus, the winding or rewinding reel can be rotated by rotating the reel support.
Referring to FIGS. 5(a) and 5(b), the reel support is rotated clockwise as indicated by the arrow, making each blade 51 abut on the confronting side of a selected projection 53 in the reel indented-aperture to transmit the torque from the reel support to the cassette reel via the blade 51. As seen from FIG. 5(a), the blade 51 is yieldingly bent counterclockwise (leftward in the drawing) to abut on the confronting inner sidewall 55 of the longitudinal slot 54. Thereafter, the blade 51 is yieldingly bent inward as indicated by the arrow, and then, it may happen that the blade 51 comes off from the projection 53, which is called xe2x80x9cblade hoppingxe2x80x9d.
Such xe2x80x9cblade hoppingxe2x80x9d can be prevented by increasing the blade""s resistance to bending. Such a stiff blade 51 will prevent the reel post from getting in the reel indented-aperture 52 when the blades 51 happen to ride on the selected projections 53 in the reel indented-aperture 52 (see FIG. 5(b); broken lines). If the reel post is press-fitted in the reel indented-aperture 52 by making the stiff blade 51 yieldingly bend inward by force (see FIG. 5(b); solid lines), the stiff blade 51 can hardly come off and fall from the projection 53 down to the inter-projection space 56 to be caught at the confronting side of the subsequent projection. Even though the stiff blade 51 slips off from the projection 53 fortunately, unpleasing sound is produced.
To prevent the blade from riding on the projection and from holding tightly each other it is necessary that the blade""s resistance to bending be reduced, but to prevent the xe2x80x9cblade hoppingxe2x80x9d it is necessary that the blade""s resistance to bending be increased. Apparently this is contradictory, and no satisfactory reel support can be designed.
The longitudinal slot 54 has a narrow gap remaining between either side of the blade 51 and the confronting inner wall 55. The blade width can be increased in the longitudinal slot by reducing the opposite gaps 57 in the slot. The so widened blade 51 can have an increased resistance to the circumferential bending as a counter action to abutment on the projection 53 (see FIG.5(a)), and accordingly the possibility of xe2x80x9cblade hoppingxe2x80x9d is reduced. The widening of the blade still permits the blade 51 to bend yieldingly inward apart from the projection 53 even if the blade 51 should ride on the projection 53. The blade 51, therefore, can come off from the projection 53 with ease.
This remedy, however, requires a metal mold whose parts to shape such narrow gaps in the longitudinal slot are too thin to be used for a long time. Thus, the life of the metal mold is reduced significantly.
One object of the present invention is to provide a reel support which is guaranteed to be free of xe2x80x9cblade hoppingxe2x80x9d and xe2x80x9ctight-holding of the blade and the projectionxe2x80x9d.
To attain this object a reel support for rotating one of the winding and rewinding reels in a magnetic tape cassette inserted in a magnetic tape recording-and-playing apparatus, is improved according to the present invention in that the reel support is a resin mold, and that the reel support comprises a support stage having a reel post and blades integrally connected to and standing upright from the support stage, the upright blades extending in the longitudinal slots made in the circumference of the upright reel post, each upright blade having a nail formed on its tip end, partially appearing from the circumference of the upright reel post to the extent of being caught by a selected projection in the indentation of the aperture of either reel; each longitudinal slot has a stepwise indent formed on one side facing the tail side of the nail of the blade, thus permitting the corner of the nail to be engaged with the stepwise indent of the one side of the longitudinal slot.
With this arrangement each blade can have a good flexibility sufficient to allow the blade to come off from the counter projection even though the blade rides thereon, falling into the inter-projection space to be caught and supported by the stepwise indent of the confronting side of the slot in the reel post. Thus, further bending of the blade which would cause the xe2x80x9cblade hoppingxe2x80x9d can be prevented effectively. Still advantageously, the stepwise indent of one inside wall of each slot permits the corresponding part of the metal mold to increase its strength.
The nail of each blade can be engaged with a selected projection in the indentation of the aperture of either reel in a plane containing the center axis of the reel support; and the corner of the nail to be engaged with the stepwise indent of the one side of the longitudinal slot is shaped so as to be complementary to the stepwise indent, but the corner of the nail is somewhat apart radially from the stepwise indent.
Other objects and advantages of the present invention will be understood from the following description of a reel support for rotating one of the winding and rewinding reels in a magnetic tape cassette according to one preferred embodiment of the present invention, which is shown in the accompanying drawings: